Messages in this thread | | | Date | Tue, 19 Sep 2006 11:32:00 -0500 | From | Olof Johansson <> | Subject | Re: [PATCH] dmaengine: clean up and abstract function types (was Re: [PATCH 08/19] dmaengine: enable multiple clients and operations) |
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On Tue, 19 Sep 2006 12:20:09 +0100 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> Ar Llu, 2006-09-18 am 20:05 -0500, ysgrifennodd Olof Johansson: > > On Mon, 18 Sep 2006 15:56:37 -0700 "Dan Williams" <dan.j.williams@gmail.com> wrote: > > > op.src_type = PG; op.src = pg; > > op.dest_type = BUF; op.dest = buf; > > op.len = len; > > dma_async_commit(chan, op); > > At OLS Linus suggested it should distinguish between sync and async > events for locking reasons. > > if(dma_async_commit(foo) == SYNC_COMPLETE) { > finalise_stuff(); > } > > else /* will call foo->callback(foo->dev_id) */ > > because otherwise you have locking complexities - the callback wants to > take locks to guard the object it works on but if it is called > synchronously - eg if hardware is busy and we fall back - it might > deadlock with the caller of dmaa_async_foo() who also needs to hold the > lock.
Good point, sounds very reasonable to me.
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